Molarity & dilution worksheet with answers

Free printable Molarity & dilution worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
250 mLc = 0.15 mol/L

What mass m of KCl (M = 74.55 g/mol) do you need to make 250 mL of a 0.15 mol/L solution?

V = 250 mLc = 0.15 mol/LM = 74.55 g/mol
m = g
2.Easy
24 g Na2​CO3​V = 100 mL

24 g of Na2CO3 (M = 105.99 g/mol) is dissolved in water to make 100 mL of solution. Find the molarity c.

m = 24 gM = 105.99 g/molV = 100 mL
c = mol/L
3.Medium
6 mol/LV1​ = ?0.5 mol/L250 mL

You need 250 mL of 0.5 mol/L solution and have a 6 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 6 mol/Lc2 = 0.5 mol/LV2 = 250 mL
V1 = mL
4.Medium
5 mol/LV1​ = ?0.3 mol/L1000 mL

You need 1000 mL of 0.3 mol/L solution and have a 5 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 5 mol/Lc2 = 0.3 mol/LV2 = 1000 mL
V1 = mL
5.Hard
0.1 mol/L200 mL0.05 mol/L100 mLc = ?300 mL

200 mL of a 0.1 mol/L solution is mixed with 100 mL of a 0.05 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.1 mol/LV1 = 200 mLc2 = 0.05 mol/LV2 = 100 mL
c = mol/L
6.Hard
0.4 mol/L250 mL0.05 mol/L500 mLc = ?750 mL

250 mL of a 0.4 mol/L solution is mixed with 500 mL of a 0.05 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.4 mol/LV1 = 250 mLc2 = 0.05 mol/LV2 = 500 mL
c = mol/L

Answer key

  1. 1. m = 2.796 g
  2. 2. c = 2.264 mol/L
  3. 3. V1 = 20.83 mL
  4. 4. V1 = 60 mL
  5. 5. c = 0.08333 mol/L
  6. 6. c = 0.1667 mol/L

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